CRISPR gene editing improves safety of leukemia bone marrow transplants

Researchers at Washington University in St. Louis have conducted a clinical trial using CRISPR-Cas9 gene editing to improve the safety of bone marrow transplants for patients with high-risk leukemia, including acute myeloid leukemia and myelodysplastic syndromes.

Traditionally, post-transplant maintenance therapies targeting the CD33 protein—which is present on many leukemia cells—also inadvertently attack healthy donor cells. To prevent this, scientists modified donor stem cells to eliminate the CD33 gene before transplantation. This approach, involving the product tremtelectogene empogeditemcel (trem-cel) developed by Vor Biopharma, aims to protect the new marrow from being destroyed by anti-CD33 drugs.

In the study involving 30 patients, all participants achieved neutrophil engraftment within 28 days. Nineteen patients subsequently received maintenance therapy, which was tolerated without prolonged hematological toxicity, indicating that the edited cells remained protected while allowing the treatment to target remaining diseased cells.